This invention relates generally to circuitry for digitizing color video signal, and then recording or storing digitized color video signal into a memory, and more particularly, the present invention relates to such a circuit useful in digital TV receiving systems, color printing systems, still picture display TV systems or the like.
Recently, color video signals used in conventional TV systems are sometimes digitally processed to be stored in a memory so that complex signal processing is allowed to obtain various kinds of reproduced pictures on a CRT or printing sheets. In a known digital system in which a color video signal, such as a composite color video signal in NTSC system, is digitized, the input composite color signal is applied to an A/D (anlog-to-digital) converter to derive digital data which will be stored in a memory. However, since the analog input including luminance and chrominance information is simultaneously converted into a digital signal by way of a single A/D converter, a relatively large number of output digital data bits is required to ensure accurate quantization.
Furthermore, in other known ditalizing system, an input composite color video signal is divided into Y, I, Q signals by way of a decoder, and then these Y, I, Q signals are used to derive three primay color signals R, G, B by way of a matrix. Then these R, G, B signals are respectively converted into digital signals by way of three different A/D converters. However, this conventional system requires three different A/D converter, while digital processing has to be effected separately for each of the three primary color signals.